1. Technical Field
This invention relates generally to heaters for performing splicing operations in waterstops and, more particularly, to a portable radiant-type heating apparatus for such purposes.
2. Discussion
Waterstops are frequently used in the construction industry for providing a water-tight seal between adjacent layers or slabs of concrete such as between wall-to-wall, or wall-to-floor, junctions and expansion junctions. Typical waterstops are made of a resilient plastic or rubber material, such as polyvinyl chloride (PVC), and generally have some sort of integral supporting members. The integral supporting members generally have laterally extending portions which are attached to reinforcing rods of the adjacent slabs prior to the pouring of concrete. The slabs of concrete are then formed with the waterstop integrally embedded therein to thereby provide a water-tight seal between the slabs of concrete. A detailed discussion of the structure and function of a typical waterstop is contained in U.S. Pat. No. 4,285,180 issued on Aug. 25, 1981 to Hinton et al. and entitled "Waterstops".
Waterstops are generally available in rolls of flat preformed sections which frequently require splicing where adjacent sections intersect. For example, it may be necessary to splice the vertically oriented waterstop bridging the joint between two adjacent wall sections with the horizontally oriented waterstop at the juncture between the walls and the floor. The resulting spliced waterstop configuration is formed to substantially match the configuration between the slabs or layers of concrete where a continuous water-tight seal is desired. Consequently, contractors are frequently required to perform various splice configurations, such as straight butt splices, T-shaped, L-shaped, cross-shaped, and other special configurations as needed to ensure a continuous waterstop seal. In practice, the special junction configurations are typically custom ordered from the waterstop manufacturer so that the contractor need only perform the simple butt-type splices to the ends of the special junction configurations in the field. However, this practice, while simplifying the type of splice performed, multiplies the total number of splices required to be performed by the contractor. Consequently, the efficiency with which the contractor can perform a splicing operation becomes extremely important.
Conventional waterstop splicing techniques generally employ a heated splicing iron for directly contacting and melting a pair of adjacent edges of two sections of waterstop. The adjacent melted edges of waterstop are then pressed together and cooled to harden and thereby form a continuous water-tight seal. Conventional splicing irons have generally employed resistance heating elements which are in direct thermal contact with a conductive metal casing. The conventional splicing iron is heated and positioned to directly contact the edges of waterstop to be spliced together.
The direct contact of the conventional splicing iron with the adjacent edges of waterstop may burn the PVC or other resilient material. The burned material may weaken the waterstop seal and further cause a charring effect and/or leave undesired contaminants within the seal. In addition, a conventional splicing iron usually requires 15 to 20 minutes to heat up and typically reaches a maximum temperature of approximately 480.degree. F. The rather lengthy heat-up time is time consuming and therefore costly to the contractor, especially when multiplied over hundreds of splices. In addition, the maximum temperature of conventional splicing irons may be inadequate to effectively perform waterstop splicing in very cold weather conditions which are common in the construction business.
It is therefore an object of the present invention to provide for an improved heating apparatus for performing splices in waterstops which does not suffer from the above-mentioned limitations associated with the conventional splicing iron. In particular, it is an object of the present invention to provide a portable radiant heating apparatus for performing splices in waterstops which does not require direct physical contact with the edges of the waterstop. In addition, it is another object of the present invention to provide a portable radiant heating apparatus which rapidly generates very high temperature radiant heat and therefore may be effectively and efficiently employed even in adverse weather conditions.